Persist photos in Excel export/import

- Add Photo column to export (base64 data URL)
- Read Photo column on import and restore flag.photoData

index.html

@@ -642,6 +642,9 @@ document.getElementById('file-input').addEventListener('change', async (e) => {
     if (!String(name).trim()) continue;
     const flag = addFlag(String(name).trim(), String(number).trim());
 
+    const photo = row.Photo || row.photo || '';
+    if (String(photo).startsWith('data:')) flag.photoData = String(photo);
+
     let lat = parseFloat(row.Latitude || row.latitude || row.위도);
     let lng = parseFloat(row.Longitude || row.longitude || row.경도);
     if (!isNaN(lat) && !isNaN(lng)) {
@@ -686,10 +689,11 @@ document.getElementById('export-btn').addEventListener('click', () => {
     Number: f.number, Name: f.name,
     Status: f.placed ? 'Placed' : 'Unplaced',
     Latitude: f.lat ?? '', Longitude: f.lng ?? '', Address: f.address ?? '',
+    Photo: f.photoData ?? '',
   }));
   const wb = XLSX.utils.book_new();
   const ws = XLSX.utils.json_to_sheet(rows);
-  ws['!cols'] = [{ wch: 12 }, { wch: 20 }, { wch: 10 }, { wch: 12 }, { wch: 12 }, { wch: 60 }];
+  ws['!cols'] = [{ wch: 12 }, { wch: 20 }, { wch: 10 }, { wch: 12 }, { wch: 12 }, { wch: 60 }, { wch: 30 }];
   XLSX.utils.book_append_sheet(wb, ws, 'Flags');
   XLSX.writeFile(wb, 'flag_export.xlsx');
 });